I just got a used copy of this and I'm a bit confused about which version I have. I viewed the information on each version here on BGG and found that if you have the 1991 reprint, the box and the rulebook have a 1991 copyright. Both my rulebook and box have the 1983 copyright so I just assumed I had the 1983 version. So I printed out the errata to note all of the changes. I always put the errata on post-it note strips so that I don't have to keep referencing the errata sheet. However, all of the additions and corrections are in my copy of the rulebook. Like with mission 5, my rulebook does not mention 22 VP needed, but 15 as the errata states. So now I think I have the 1991 version, yet I have a 1983 copyright.

Is my latter statement correct? Are there any other ways to tell what version you have? Is the rulebook the only difference?

Mine is the same - bought in 1991 but copyright is 1983 on both the box and rulebook. I think the main way to tell is that most of the errata was corrected by the 1991 edition. Not sure if that helps. Great game though.

No expert here, but it seems likely that they had extra components (boxes, maps and counters) and reprinted rules and missions to fill out the parts. This seems like a common theme in small publishing where the publishers order extra counters to cover miscut sheets.

My copy of the game says Copyright 1983/1991. Everything (the rulebook, the paragraph booklet, charts, etc.) has the same copyright date (1983/1991). The errata seem to have been applied to the rulebook at least as my mission #5 also says only 15 VP needed.